flush property
Flushes this collection, if necessary. Chainable method.
If collection list is already flushed, don't do anything.
Note: This will flush the map and all its internal sets.
Implementation
@override
IMapOfSets<K, V> get flush {
_mapOfSets.flush;
_mapOfSets.values.forEach((ISet<V> s) => s.flush);
return this;
}